Model Based Signal Enhancement for Impulse Response Measurement PDF Download

Author: Xun Wang
Publisher: Logos Verlag Berlin GmbH
ISBN: 3832536302
Category : Computers
Languages : en
Pages : 148

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Book Description
Impulse response measurements that are performed outdoors are highly susceptible to the uncertainties caused by the non-perfect measurement setup, the presence of background noise, and fluctuations in media such as wind and temperature drift. This work concentrates on two scenarios: the measurement of reflection coefficients of noise barriers and the influence of temperature variances in machinery cavities. Regarding the sound barrier measurement outdoors, a linear four-microphone array can be used to separate direct sound and reflected sound if the sound barrier does not include complicated scattering structures. With regard to the impulse response of an air-borne sound measurement for a machine monitoring system, a time-warping model for inter-period and intra-period temperature variances is investigated.

Author: Pascal Dietrich
Publisher: Logos Verlag Berlin GmbH
ISBN: 3832535519
Category : Technology & Engineering
Languages : en
Pages : 220

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Book Description
Measured transfer functions of acoustic systems are often used to derive single-number parameters. The uncertainty analysis is commonly focused on the derived parameters but not on the transfer function as the primary quantity. This thesis presents an approach to assess the uncertainty contributions in these transfer functions by using analytic models. Uncertainties caused by the measurement method are analyzed with a focus on the underlying signal processing. In particular, the influence of nonlinearities in the acoustic measurement chain are modeled to predict artifacts in the measured signals and hence the calculated acoustic transfer function. Secondly, characterization methods commonly applied in the field of signal processing are linked to the acoustic scenarios and the main influencing parameters. Acoustic parameters are then derived analytically and by means of Monte Carlo simulations considering the uncertainty of these input parameters. In order to provide airborne applications, analytic models for sound barrier and room acoustic measurements are developed incorporating the directivity and the orientation of the sound source as well as the positions of sources and receivers. The simulated uncertainty contributions are validated by measurements. The same approach is also applied to structure-borne sound applications.

Author: Ramona Bomhardt
Publisher: Logos Verlag Berlin GmbH
ISBN: 3832545433
Category : Science
Languages : en
Pages : 162

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Book Description
Human sound localization helps to pay attention to spatially separated speakers using interaural level and time differences as well as angle-dependent monaural spectral cues. In a monophonic teleconference, for instance, it is much more difficult to distinguish between different speakers due to missing binaural cues. Spatial positioning of the speakers by means of binaural reproduction methods using head-related transfer functions (HRTFs) enhances speech comprehension. These HRTFs are influenced by the torso, head and ear geometry as they describe the propagation path of the sound from a source to the ear canal entrance. Through this geometry-dependency, the HRTF is directional and subject-dependent. To enable a sufficient reproduction, individual HRTFs should be used. However, it is tremendously difficult to measure these HRTFs. For this reason this thesis proposes approaches to adapt the HRTFs applying individual anthropometric dimensions of a user. Since localization at low frequencies is mainly influenced by the interaural time difference, two models to adapt this difference are developed and compared with existing models. Furthermore, two approaches to adapt the spectral cues at higher frequencies are studied, improved and compared. Although the localization performance with individualized HRTFs is slightly worse than with individual HRTFs, it is nevertheless still better than with non-individual HRTFs, taking into account the measurement effort.

Author: Stefan Feistel
Publisher: Logos Verlag Berlin GmbH
ISBN: 3832537104
Category : Computers
Languages : en
Pages : 224

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Book Description
Starting from physical theory, this work develops a novel framework for the acoustic simulation of sound radiation by loudspeakers and sound reinforcement systems. First, a theoretical foundation is derived for the accurate description of simple and multi-way loudspeakers using an advanced point-source ''CDPS'' model that incorporates phase data. The model's practical implementation is presented including measurement requirements and the GLL loudspeaker data format specification. In the second part, larger systems are analyzed such as line arrays where the receiver may be located in the near field of the source. It is shown that any extended line source can be modeled accurately after decomposition into smaller CDPS elements. The influence of production variation among elements of an array is investigated and shown to be small. The last part of this work deals with the consequences of fluctuating environmental conditions such as wind and temperature on the coherence of sound signals from multiple sources. A new theoretical model is developed that allows predicting the smooth transition from amplitude to power summation as a function of the statistical properties of the environmental parameters. A part of this work was distinguished with the AES Publications Award 2010. Parts of the proposed data format have been incorporated into the international AES56 standard.

Author: James V. Candy
Publisher: John Wiley & Sons
ISBN: 0471732664
Category : Technology & Engineering
Languages : en
Pages : 702

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Book Description
A unique treatment of signal processing using a model-based perspective Signal processing is primarily aimed at extracting useful information, while rejecting the extraneous from noisy data. If signal levels are high, then basic techniques can be applied. However, low signal levels require using the underlying physics to correct the problem causing these low levels and extracting the desired information. Model-based signal processing incorporates the physical phenomena, measurements, and noise in the form of mathematical models to solve this problem. Not only does the approach enable signal processors to work directly in terms of the problem's physics, instrumentation, and uncertainties, but it provides far superior performance over the standard techniques. Model-based signal processing is both a modeler's as well as a signal processor's tool. Model-Based Signal Processing develops the model-based approach in a unified manner and follows it through the text in the algorithms, examples, applications, and case studies. The approach, coupled with the hierarchy of physics-based models that the author develops, including linear as well as nonlinear representations, makes it a unique contribution to the field of signal processing. The text includes parametric (e.g., autoregressive or all-pole), sinusoidal, wave-based, and state-space models as some of the model sets with its focus on how they may be used to solve signal processing problems. Special features are provided that assist readers in understanding the material and learning how to apply their new knowledge to solving real-life problems. * Unified treatment of well-known signal processing models including physics-based model sets * Simple applications demonstrate how the model-based approach works, while detailed case studies demonstrate problem solutions in their entirety from concept to model development, through simulation, application to real data, and detailed performance analysis * Summaries provided with each chapter ensure that readers understand the key points needed to move forward in the text as well as MATLAB(r) Notes that describe the key commands and toolboxes readily available to perform the algorithms discussed * References lead to more in-depth coverage of specialized topics * Problem sets test readers' knowledge and help them put their new skills into practice The author demonstrates how the basic idea of model-based signal processing is a highly effective and natural way to solve both basic as well as complex processing problems. Designed as a graduate-level text, this book is also essential reading for practicing signal-processing professionals and scientists, who will find the variety of case studies to be invaluable. An Instructor's Manual presenting detailed solutions to all the problems in the book is available from the Wiley editorial department

Author: Franz Zotter
Publisher: Springer
ISBN: 3030172074
Category : Technology & Engineering
Languages : en
Pages : 223

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Book Description
This open access book provides a concise explanation of the fundamentals and background of the surround sound recording and playback technology Ambisonics. It equips readers with the psychoacoustical, signal processing, acoustical, and mathematical knowledge needed to understand the inner workings of modern processing utilities, special equipment for recording, manipulation, and reproduction in the higher-order Ambisonic format. The book comes with various practical examples based on free software tools and open scientific data for reproducible research. The book’s introductory section offers a perspective on Ambisonics spanning from the origins of coincident recordings in the 1930s to the Ambisonic concepts of the 1970s, as well as classical ways of applying Ambisonics in first-order coincident sound scene recording and reproduction that have been practiced since the 1980s. As, from time to time, the underlying mathematics become quite involved, but should be comprehensive without sacrificing readability, the book includes an extensive mathematical appendix. The book offers readers a deeper understanding of Ambisonic technologies, and will especially benefit scientists, audio-system and audio-recording engineers. In the advanced sections of the book, fundamentals and modern techniques as higher-order Ambisonic decoding, 3D audio effects, and higher-order recording are explained. Those techniques are shown to be suitable to supply audience areas ranging from studio-sized to hundreds of listeners, or headphone-based playback, regardless whether it is live, interactive, or studio-produced 3D audio material.

Author: T. K. Sarkar
Publisher: John Wiley & Sons
ISBN: 0471721239
Category : Technology & Engineering
Languages : en
Pages : 473

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Book Description
A valuable addition to the Wiley Series in Microwave and Optical Engineering Today's modern wireless mobile communications depend on adaptive "smart" antennas to provide maximum range and clarity. With the recent explosive growth of wireless applications, smart antenna technology has achieved widespread commercial and military applications. The only book available on the topic of adaptive antennas using digital technology, this text reflects the latest developments in smart antenna technology and offers timely information on fundamentals, as well as new adaptive techniques developed by the authors. Coupling electromagnetic aspects of antenna design with signal processing techniques designed to promote accurate and efficient information exchange, the text presents various mechanisms for characterizing signal-path loss associated with signal propagation, particularly for mobile wireless communications systems based on such techniques as joint space-frequency adaptive processing. In clear, accessible language, the authors: * explain the difference between adaptive antennas and adaptive signal processing * Illustrate the procedures for adaptive processing using directive elements in a conformal array * clarify multistage analysis procedure which combines electromagnetic analysis with signal processing * present a survey of the various models for characterizing radio wave propagation in urban and rural environments * describe a method wherein it is possible to identify and eliminate multipath without spatial diversity * optimize the location of base stations in a complex environment The text is an excellent resource for researchers and engineers working in electromagnetics and signal processing who deal with performance improvement of adaptive techniques, as well as those who are concerned with the characterization of propagation channels and applications of airborne phased arrays.

Author: Roland Bammer
Publisher: Lippincott Williams & Wilkins
ISBN: 1469889625
Category : Medical
Languages : en
Pages : 2558

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Book Description
Essential reading for both clinicians and researchers, this comprehensive resource covers what you need to know about the basic principles of perfusion, as well as its many clinical applications. Broad coverage outlines the overarching framework that interlinks methods such as DSC, DCE, CTP, and ASL. International experts in the field demonstrate how perfusion and pharmacokinetic imaging can be effectively used to analyze medical conditions, helping you reach accurate diagnoses and monitor disease progression and response to therapy.

Author: Ehsan Samei
Publisher: Springer Nature
ISBN: 3030269574
Category : Medical
Languages : en
Pages : 469

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Book Description
This book offers a comprehensive and topical depiction of advances in CT imaging. CT has become a leading medical imaging modality, thanks to its superb spatial and temporal resolution to depict anatomical details. New advances have further extended the technology to provide physiological information, enabling a wide and expanding range of clinical applications. The text covers the latest advancements in CT technology and clinical applications for a variety of CT types and imaging methods. The content is presented in seven parts to offer a structure across a board coverage of CT: CT Systems, CT Performance, CT Practice, Spectral CT, Quantitative CT, Functional CT, and Special Purpose CT. Each contain chapters written by leading experts in the field, covering CT hardware and software innovations, CT operation, CT performance characterization, functional and quantitative applications, and CT systems devised for specific anatomical applications. This book is an ideal resource for practitioners of CT applications in medicine, including physicians, trainees, engineers, and scientists.

Author: Judith Rizoli White
Publisher: Institute of Electrical & Electronics Engineers(IEEE)
ISBN: 9780780389892
Category : Science
Languages : en
Pages : 176

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Book Description